Thanks for the reply. Yes, it would help if there had been more responses, but someone has to be first I suppose.
I have done a fair bit of research on this and decided to get a quote from Warrantywise. My CX5 has only done 17,000 miles (we have two cars) and has full dealer service history. My quote from them was near £900.00 for 12 months. During a follow up call, which was unsolicited, they dropped it to around £280.00 but obviously with lower cover. That made my mind up not to use them.
I have decided to stick with Mazda. They only use Mazda service for any neccessary repairs.